The present invention relates, in general, to electronics, and more particularly, to electron emission devices.
One of the recent advances in vacuum microelectronics led to the use of nanotubes as electron emitters. Typically, nanotubes are fine filaments made from carbon as disclosed by Cees Deckker, Carbon Nanotubes as Molecular Quantum Wires, Physics Today, pp. 22-28, May 1999. The nanotubes are applied to a substrate to function as electron emitters. Typically, the nanotubes disposed on the substrate have a random orientation. Because of this random orientation, the emitters and devices using the emitters have a low efficiency, measured as anode current divided by cathode current. Typically, the efficiency is less than three percent. Additionally these devices often have high leakage current, measured as gate current divided by cathode current. The leakage current generally is greater than ninety-seven percent.
Accordingly, it is desirable to have a formation method that results in electron emitters that have a high efficiency (greater than three percent) and a low leakage current (less than ninety-seven percent).
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well known steps and elements are omitted for simplicity of the description.